1. Field of the Disclosure
The present disclosure relates generally to alignment assemblies for an imaging device, and, more particularly, to a bump alignment assembly and a method of using the same.
2. Description of the Related Art
Currently, most imaging devices position a bump align assembly in the media path prior to an image transfer station and/or a fuser to align the media prior to toned image transfer or fusing. This is done to minimize skew between the media sheet and the toned image that is to be transferred to the media sheet. An illustration of such a prior art assembly 1 is shown in FIG. 1. The media process direction is indicated by the arrow A. The plane of the media path is into the plane of the page. A bump alignment roll pair 10 is positioned downstream of a pair of spaced media guides 15, 16, while a media feed roll pair 12 is positioned upstream of the media guides 15, 16. A bubble chamber 18 is formed between media guides 15, 16. In prior art imaging devices, the bump alignment assembly 1 required that the media sheets being inputted to the bump alignment assembly 1 be from a single media path. However, most imaging devices have two or more media paths that will provide media for further processing such as toned image transfer or fusing operations. For example, media sheets may be fed from duplex path 50 formed between media guides 40, 42, 44 and along media path 52 formed between media guides 44, 46 from input media tray 30 holding a media stack MST. Also shown is a third media input path 54 between media guides 42, 44. Media path 54 may be from a multipurpose feeding tray, another option assembly, or a manual input tray. Auxiliary media feed roll pairs 14 are shown along each of paths 50 and 52 and are used to direct media sheets to media feed roll pair 12. With such an arrangement, the two input media paths 50, 52, feeding roll pair 12 need to be merged into a single media path that will allow a media sheet being fed along either media path 50, 52 to be directed into nip 13 of media feed roll pair 12. This is done through a transition section 56 provided in the media path upstream of feed nip 13 of media feed roll pair 12. Extension section 56 is shown as extensions of media guides 40, 44, and 46. The transition section 56 increases the length of the media path and the height or depth of the imaging device, depending on the orientation of the bump alignment assembly 1. As shown, the height of the imaging device would be increased, in some cases by about 45 mm or more, due to transition section 56. It would be advantageous to have a bump alignment assembly that can accommodate two or more input media paths without increasing the length of the media path and without increasing the overall height or depth of the imaging device.
Media sheet M is fed from media tray 30 through media feed roll pairs 14, 12, then between media guides 15, 16 and into bump align roll pair 10 that is either stopped or rotating opposite to the media process direction A. After the leading edge LE of the media sheet M contacts the nip 11 in bump alignment roll pair 10, media feed roll pair 12 and, if needed, media feed roll pair 14, continue to feed media sheet M into the bubble chamber 18 causing the media sheet M to buckle in a direction controlled by the media guides 15, 16, and eventually form a bubble B in bubble chamber 18. The bubble B allows the leading edge LE of media sheet M to align with the nip 11 of the bump alignment roll pair 10, deskewing the leading edge LE of media sheet M. The bump alignment roll pair 10 are then rotated to feed the media sheet M in the media process direction A for further processing.
With prior art bump alignment assemblies media edge sensors 20 having moveable arms 22 are provided by the media feed roll pair 12 and the bump alignment roll pair 10 for detecting the leading and trailing edges of the media sheet M being fed into and through the bubble chamber 18. Arms 22 are typically positioned at about 90 degrees to the media process direction across the media path. A third media sensor 23, similar to media edge sensors 20, has a specialized fan-shaped arm 24 and is provided in the bubble chamber 18 to sense and control bubble growth. The fan-shaped arm 24 is designed to be positioned at about 180 degrees with respect to media feed path so that it senses a force applied by the bubble B as it grows out from the media feed path. It would be advantageous to be able to eliminate one of the media sensors but still maintain the detection of media edges and control of bubble formation.